This invention relates to a screw-nut screw coupling with ball circulation.
In particular, the invention relates to a screw-nut screw coupling with ball circulation, in which the nut screw is provided with at least one internal recirculation channel extending between two adjacent turns.
Nut screws of the aforesaid type are normally employed in all those applications in which the advantages deriving from the use of a screw-nut screw coupling with ball circulation must be associated with relatively low constructional costs.
In known nut screws of the aforesaid type, each recirculation channel is defined by a groove provided on the end of a block mounted in a respective radial through bore provided in said nut screw and embracing two adjacent internal turns thereof. The block is positioned in such a manner that the relative groove connects together the two aforesaid turns and enables the balls to pass from one to the other.
The use of relatively economical materials and progress in the methods for manufacturing screws and nut screws have enabled the production costs of the aforesaid couplings to be considerably reduced. However, these costs remain relatively high because the operations involved in introducing the balls between the screw and nut screw continue to be carried out manually and are more laborious the smaller the diameter of the balls used.